Installation for treating, in particular for coating, articles, especially vehicle bodies

ABSTRACT

An installation for treating, in particular coating, articles, especially vehicle bodies, comprises at least one bath, in which a treatment liquid, in particular a paint, is located. The articles are intended to be immersed therein. A conveyor with which the articles are conveyed through the installation in a continuous or intermittent translational movement comprises a plurality of transport carriages, which run in guided manner on running surfaces. Each transport carriage comprises a separate drive for translational movement and a drive operating independently thereof for the immersion movement. The installation thus constructed is extraordinarily flexible, since the immersion movement does not have to correlate with the translational movement. The transport carriages, optionally carrying different articles, may miss from different directions at different speeds, travel at different speeds and thereby enlarge or reduce distances from preceding transport carriages and, if required, be individually removed from the transport line.

The invention relates to an installation for treating, in particularcoating, articles, especially vehicle bodies, having

a) at least one bath, in which a treatment liquid, in particular apaint, is located, in which the articles are intended to be immersed;

b) a conveying means, with which the articles may be conveyed throughthe installation in a continuous or intermittent translational movement;

c) a plurality of immersion means, which are connected with theconveying means, each carry one article and are in a position to immersethis article in the bath.

An installation of this type is described in DE 196 41 048 C2. Theconveying means therein consists of guide rails, in which there rundrive means, not described in any more detail; examples of these drivemeans are chains, hauling ropes, geared rods or the like. A plurality ofmounting frameworks for the bodies to be coated are connected with thedrive means at regular intervals and are displaced translationallythereby. The translational movements of all the bodies to be coated arein this way compulsorily coupled together. The bodies are immersed inand extracted from the treatment fluid by rotary motion of the mountingframeworks about an axis, which extends horizontally and perpendicularlyto the direction of the translational movement. The forces which rotatethe mounting frameworks are derived from the translational movement by akind of cam/crank means, such that the instantaneous angle of rotationof the mounting frameworks always clearly results from the position ofthe mounting framework in the direction of translation.

A disadvantage of this known installation is its lack of flexibility: asalready mentioned, all the articles to be coated can only move jointlyin the transport direction. Thus, all the articles in the installationhave to pass through the baths in the same way, with the same kinematicsand at the same speed. This frequently does not fulfil the requirementsof a modern installation, in which successive articles need to betreated in different ways.

The object of the present invention is so to design an installation ofthe above-mentioned type that it allows altogether more flexibletreatment of the individual articles.

This object is achieved according to the invention in that

d) the conveying means comprises a plurality of independent transportcarriages, which run in guided manner on running surfaces and eachcomprise a separate drive for translational movement and a driveoperating independently thereof for the immersion movement.

According to the invention, therefore, the rigid coupling present in theprior art between the various mounting frameworks is abandoned andreplaced by a plurality of individual transport carriages, which maybasically move independently of one another. Each of these transportcarriages has its own drive for translational movement. The speeds ofthe individual transport carriages may thus be independently selected;the intervals between successive transport carriages may be enlarged orreduced. It is additionally possible to guide the immersion movement ofthe articles independently of the translation movement, since a separatedrive is provided for this immersion movement. Thus, for instance a bathmay be missed out, simply by not actuating the drive of the carriage forthe immersion movement at the appropriate point in the transport path.It is also possible firstly to miss out a bath and then to perform thearticle immersion process in a backwards movement. This immersiondirection may be more favourable than an immersion movement in theforwards direction in particular in the case of bodies which have doorswhich come open or the like. Moreover, each article to be coated may beindividually subjected to a swinging movement within the bath. Articlescomprising cavities, like vehicle bodies, may be completely emptiedabove the respective bath by suitable movements, such that as little aspossible of the paint is entrained out of the bath. The speed of thetranslational movement may be reduced above and in the baths, soresulting in long residence times therein, while the speed oftranslation between the baths may be increased. Loading and delivery ofthe articles to be treated may, on the other hand, be performed at astandstill. Altogether, the shortest possible bath lengths may beachieved in this way, such that the space requirement of the overallsystem is reduced.

In the case of a fault, individual transport carriages may easily beremoved from the installation. The risk of bath contamination is reducedin that all conveying system components may be arranged laterally of thebaths.

An advantageous further development of the installation according to theinvention is distinguished in that at least one vertically orientedtransport flange extends parallel to a running surface and in that thedrive for the translational movement of each transport carriagecomprises a pressure roll drive, which comprises at least two pressurerolls running under pressure on opposing side faces of the transportflange, at least one of which pressure rolls is driven. Drive of thetransport carriages for the translational movement thus proceeds not viathe running wheels themselves but rather via the above-mentioned,separate pressure roll drive, which interacts with the stationarytransport flange. This simplifies control of the transport carriages ontheir path through the installation. Moreover, good acceleration anddeceleration may be achieved with such a drive.

The running wheels of the transport carriages may be rotated about avertical axis by means of a pivoted bolster. In this embodiment of theinvention, the running wheels are thus steerable, which reduces wear andprecision requirements for instance in comparison with normal railrunning wheels. In particular, by appropriately rotating the pivotedbolsters of the running wheels about the perpendicular axis, thetransport carriages may also be moved sideways out of the conveyingline, perpendicularly to their longitudinal extension.

At least two wheels of each transport carriage are preferably providedwith a leading guide member, which encompasses a profile of theassociated running surface and is connected with the pivoted bolster.The transport carriages are conveyed through the installation by theseguide members, wherein cornering is straightforwardly possible. Theother two wheels of the transport carriages do not need to be guided;they may take the form of simple follower wheels.

The precise configuration of the mounting and guidance of the runningwheels and the design of the running wheels themselves may be based onthe constructions described in DE 44 27 191 C2, DE 197 44 446 A1 andalso DE 199 34 746 A1.

The immersion means may be a rotary means, which immerses the articlesin the treatment liquid by rotation about an approximately horizontalaxis. The present invention may thus also be used in the case ofimmersion kinematics as put into practice in the above-described DE 19641 048 C2.

An exemplary embodiment of the invention is explained in more detailbelow with reference to the drawings, in which

FIG. 1: shows a perspective portion of a dip-coating installation forvehicle bodies;

FIG. 2: shows a section through the installation of FIG. 1perpendicularly to the direction of movement of the vehicle bodies,viewed form the bottom right;

FIG. 3: is a side view of the portion of the coating installation ofFIG. 1;

FIG. 4: is a side view of a transport carriage used in the coatinginstallation, having a vehicle body attached thereto;

FIG. 5: is a perspective view of the transport carriage plus vehiclebody of FIG. 4;

FIG. 6: shows an enlarged detail taken from the area of the circlelabelled with letter A in FIG. 2;

FIG. 7: shows an enlarged detail from the area of the circle labelledwith letter B in FIG. 2.

The dip-coating installation for vehicle bodies illustrated in thedrawings includes a steel structure 1 comprising a plurality of verticalposts and horizontal beams, in which steel structure 1 there aresuspended two bath containers 2, 3. The bath containers 2, 3 are filledup to a given level with liquid paint, in which vehicle bodies 4 areintended to be immersed. To this end, these vehicle bodies 4 aretransported with the aid of individual transport carriages 5 in thedirection of the arrow 6 (c.f. FIG. 1), wherein this translationalmovement of the individual transport carriages 5 may proceedindependently for each one and deceleration, acceleration, stops andeven reversal of movement are possible in the course of theseindependent movements. However, all in all the vehicle bodies 4 areconveyed in the direction of the arrow 6 in FIG. 1.

The precise construction of the transport carriages 5 is shown in moredetail in FIGS. 4 to 7. As shown in particular in FIG. 5, each transportcarriage 5 has two longitudinal rails 7, 8, on the undersides of whichthere are mounted in each case two twin wheels 9, 10 and 11, 12respectively, so as to be rotatable about horizontal axes. In addition,the wheels 9 to 12 may each rotate about a vertical axis by means of apivoted bolster, not described in detail, such that the orientation ofthe twin wheels 9 to 12 may be altered relative to the respectivelongitudinal rails 7, 8.

The twin wheels 9, 10 roll on a first running surface 13 and the twinwheels 11, 12 on a second running surface 14 parallel thereto. Therunning surfaces 13, 14 are in turn mounted in each case on I-beams 15,16, which are carried by the steel structure 1 (c.f. in particular FIG.2.

In the middle of the first running surface 13, the lower one in FIG. 5,there is fitted a guide rib 17, which is gripped by guide members 18comprising complementary recesses. Each guide member 18 is connectedwith the pivoted bolster of an associated twin wheel 9 or 10respectively in such a way that it rotates this twin wheel 9 or 10 aboutthe vertical axis in accordance with the course of the guide rib 17. Inthis way, the twin wheels 9, 10 follow the first running surface 13. Thetwin wheels 11, 12 associated with the second running surface 14, theupper one in FIG. 5, are designed, on the other hand, as simple followerwheels; that is to say, no separate guide means are provided forinfluencing the angular position of the wheels about their vertical axisof rotation. In this way, precision requirements relating to the guidemeans with which the transport carriages 5 are kept on the runningsurfaces 13, 14 may be kept low.

In the middle of each of the two longitudinal rails 7, 8 of thetransport carriages 5 there is mounted a gear block 19 or 20respectively, the driven shafts of which are connected by a rotary shaft21. On the rotary shaft 21 there are attached, spaced from one another,two fixing plates 22, 23 triangular in form in side view. On the longestedges, normally pointing upwards, of these triangles the vehicle bodies4 are attached in a suitable manner, not shown.

An electric motor 24 or 25 respectively is flanged onto each of the gearblocks 19, 20. The arrangement is such that, when current is supplied tothe electric motors 24, 25, the rotary shaft 21 is rotated in aparticular direction, wherein forces are introduced thereinto from bothsides. Rotation of the rotary shaft 21 is accompanied by a correspondingrotation of the bodies 4 about the axis of the rotary shaft 21.

The twin wheels 9 to 12 of the transport carriages 5 are not themselvesdriven. Forwards drive of the transport carriages 5 is effected insteadvia a separate drive, which is explained in more detail below withreference to FIGS. 5 to 7.

Parallel to the two running surfaces 13, 14 there extend twoperpendicularly oriented, stationary drive flanges 26, 27. These eachinteract with a pressure roll drive 28 or 29 respectively, which isattached to the side face of the adjacent longitudinal rail 7, 8 bymeans of a lug 30 or 31 respectively. The pressure roll drives 28, 29each comprise an electric drive motor 32, 33 and a drive gear 34, 35.The latter drives the parallel, vertical axles of two pressure rolls 36,37 or 38, 39, which are pressed from both sides against the respectivelyassociated drive flange 26 or 27. If current is fed to the drive motors32, 33, the pressure rolls 36, 37 or 38, 39 run on the respective sidefaces of the drive flanges 26, 27 and in so doing move the transportcarriage 5 forwards on the running surfaces 13, 14.

Each transport carriage 5 comprises its own carriage control system,under the control of which it performs both its translational movementalong the running surfaces 13, 14 and the rotary movement of the vehiclebodes 4 about the axis of the rotary shaft 21.

The above-described dip-coating installation operates overall asfollows:

The vehicle bodies to be coated are fed to the baths 3, 4 in succession,each on their own transport carriage 5. Once the leading end of avehicle body 4 has reached the beginning of the first bath 2 in thetransport direction 6, the carriage control system decides whether thisvehicle body 4 should be immersed in this bath 2. If yes, the electricmotors 24, 25 are supplied with current. The electric motors aresupplied with current in accordance with the speed of the translationalmovement, which is preset by the pressure roll drives 28, 29, and thevehicle body 4 is rotated about the axis of the rotary shaft 21 andimmersed in the paint contained in the bath 2. Depending onrequirements, the translational movement of the transport carriage 5 maybe slowed down or stopped when the vehicle body 4 is immersed and thevehicle body 4 subjected to a swinging movement, by energising theelectric motors 24, 25 alternately in opposing directions. After thedesired residence time in the bath 2, the vehicle body 4 is lifted backout of the bath 2 by actuation of the electric motors 24, 25 androtation about the axis of the rotary shaft 21.

If necessary, the vehicle body 4 may be brought into different angularpositions above the bath 2 by appropriately energising the electricmotors 24, 25, in order to allow the paint to run and drip as fully aspossible back into the associated bath 2 and in this way to minimisepaint entrainment. Then, by actuating the pressure roll drives 28, 29,the translational movement of the transport carriage 5 is resumed,optionally at a higher speed, until the vehicle body 4 has reached thesecond bath 3, in the direction of movement. The same processes may thenbe repeated as were described for the first bath 2.

In certain coating installations, different vehicle bodies 4 follow oneanother which have to be treated in different ways. This isstraightforwardly possible with the coating installation described. Forexample, a bath 2, 3 may be missed out completely; the vehicle body 4may also be immersed in the bath 2, 3 in question by a rearwardlydirected, combined rotary and translational movement. “Lifting” thevehicle body 4 out of the bath 2, 3 may be performed by continuing therotary movement in the direction of rotation in which the immersionprocess took place; alternatively, it is also possible to rotate thevehicle body 4 back out of the bath 2, 3 on the same side as it waspreviously immersed therein by reversing the direction of rotation ofthe rotary shaft 21.

Since, as mentioned, successive vehicle bodies 4 may be treated in thebaths 2, 3 in different ways, different intervals may be set betweensuccessive transport carriages 5. These different intervals may beevened out again if desired by appropriate acceleration or decelerationof successive transport carriages 5.

At the beginning of the coating installation, there is located a loadingstation, not shown, at which the individual vehicle bodies 4 arepositioned on a stationary transport carriage 5 and attached thereto.Likewise, at the end of the coating installation there is located aremoval station, at which the vehicle bodies 4 are removed from astationary transport carriage 5. Both the loading and the removalstation take the form of lifting stations. In the removal station, theemptied transport carriage 5 is lowered until the running surfaces 13,14, which also continue into the removal station, are aligned withparallel running surfaces 13′, 14′, which extend back in a lower storeyof the steel structure 1 as far as the loading station. The emptytransport carriages 5 are brought on these running surfaces 13′, 14′under the baths 2, 3 contrary to the direction of arrow 6 to the loadingstation, a procedure which may be performed at a higher speed. In theloading station, the transport carriages 5 are again raised to the levelof the upper running surfaces 13, 14 and, as already described, loadedwith new vehicle bodies 4 to be coated.

As is clear from FIG. 1 in particular, all the conveying systemcomponents of the coating installation described are located laterallyof the baths 2, 3, such that the liquids in the baths 2, 3 cannot becontaminated by these conveying system components.

What is claimed is:
 1. An installation for treating, in particularcoating, articles, especially vehicle bodies, having: a) at least onebath, in which a treatment liquid, in particular a paint, is located, inwhich the articles are intended to be immersed; b) a conveying means,with which the articles may be conveyed through the installation in acontinuous or intermittent translational movement; c) a plurality ofimmersion means, which are connected with the conveying means, whereineach immersion means carries one article and are in a position toimmerse the article in the at least one bath, characterized in that; d)the conveying means comprises a plurality of independent transportcarriages, which run in guided manner on running surfaces and eachcomprise a separate drive for translational movement and a driveoperating independently thereof for an immersion movement.
 2. Aninstallation according to claim 1, characterized in that at least onevertically oriented transport flange extends parallel to a runningsurface and in that the drive for the translational movement of eachtransport carriage comprises a pressure roll drive, which comprises atleast two pressure rolls running under pressure on opposing side facesof the transport flange, at least one of which pressure rolls is driven.3. An installation according to claim 1, characterized in that runningwheels of the transport carriages may be rotated about a vertical axisby means of a pivoted bolster.
 4. An installation according to claim 3,characterized in that at least two running wheels of each transportcarriage are provided with a leading guide member, which encompasses aprofile of the associated running surface and is connected with thepivoted bolster of the associated running wheel.
 5. An installationaccording to claim 1, characterized in that the immersion means is arotary means, which immerses the articles in the treatment liquid byrotation about an approximately horizontal axis.